This research aims to test (1) the effectiveness between problem posing learning model with Indonesian realistic mathematical education approach and problem posing learning model on written mathematical communication skills, (2) the effectiveness between field-independent and field-dependent cognitive styles on written mathematical communication skills, (3) the effectiveness between problem posing learning model with Indonesian realistic mathematical education approach and problem posing learning model on the written mathematical communication skills from each cognitive style, and (4) the effectiveness between field-independent and field-dependent cognitive styles on written mathematical communication skills from each learning model. This quantitative research employed a quasi-experimental method. The research sample consisted of 240 fifth-grade elementary school students in Jebres District, Surakarta, Indonesia. Data collection techniques included tests of written mathematical communication skills and cognitive styles. The data were analyzed using prerequisite (normality, homogeneity, and balance), hypothesis, and multiple-comparison tests. The findings prove that (1) PP model with Indonesian realistic mathematical education approach is more effective than the PP and direct instruction models, (2) field-independent cognitive style is better than field dependent, (3) PP with Indonesian realistic mathematical education is as effective as the PP model, but more effective than the direct instruction model, and the PP model is more effective than the direct instruction model in each cognitive style, and (4) in the PP learning model with Indonesian realistic mathematical education approach, field-independent cognitive style is same skill as with field-dependent, but field-independent is better than field-dependent cognitive style in the PP and direct instruction learning models.

The objective of this research is to analyze the twelfth graders' mathematics critical thinking skills using a mathematics learning model to stimulate fundamental critical thinking abilities of science courses in SMA Negeri, Pacitan Regency, East Java Province, Indonesia. This quasi-experimental research design was used in this study with one group posttest only design using multiple substantive posttests. The sample of 141 students from the total population of six public schools involving the twelfth graders of the natural sciences was selected through purposive sampling technique, data were taken through tests of students' critical thinking skills and interviews. The data analysis consists of five stages, namely an analysis of one sample t-test, an analysis of students' grades, an analysis of problem-solving stages, an analysis of critical thinking abilities indicators, and an analysis of mathematics critical thinking abilities indicators. The results showed (1) The results of the one sample t-test show that the mathematics learning model is effective to stimulate critical thinking, which means that the application of the mathematics learning model is effective to stimulate critical thinking; (2) the overall grades of students that met the minimum mastery criteria; (3) the data analysis of eleven problem-solving stages proves that the criteria for critical thinking abilities are categorized as good and very good. The highest score indicator considers the principle and definition of transformation, while the lowest grade indicator is mainly concerned with the questions on right and coherent steps; (4) the critical thinking skills have seven indicators that highlight the criteria of students' critical thinking abilities categorized as good and very good. The indicators that get the highest score determine the definitions of terms, while the indicators of the lowest score determine the action; (5) the results of the analysis show indicators of mathematics critical thinking skills that have eight indicators. The criteria of students' critical thinking abilities met good and very good categories along with indicators with the highest value score by considering the definitions of terms, while the indicators of the lowest score deal with the habit of caution.

The Think-Pair-Share (TPS) strategy makes the learning environment interactive, lively, collaborative and democratic. It allows students to interact; accept information; develop collaborative discussion skills; refine their thinking; and participate effectively in the classroom. In this study, the researchers investigated the effect of the collaborative discussion strategy (think-pair-share) on developing students' skills in solving engineering mathematical problems. Once we had confirmed the validity and reliability of the tools, we used the quasi-experimental approach. The study sample consisted of 66 students divided into two groups: Namely, an experimental group, which comprised 33 students who studied mathematics using the (think-pair-share) strategy; and a control group, which comprised 33 students who studied in the traditional way. Both groups sat for a pretest and post-test in mathematics. The test results showed that the use of the TPS strategy had a positive effect on developing problem-solving skills compared to the traditional method. In light of these results, the study recommended the use of TPS strategy to improve the skills of students in solving engineering mathematical problems.